simple observer readme

Polymer · Dec 26, 2017 · d48967d · d48967d
1 parent 9bcac25
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diff --git a/README.md b/README.md
@@ -126,6 +126,14 @@ class TestElement extends Polymer.Element {
   @property()
   bar: string = 'yes';
 
+  // @observe does not support simple observers,
+  // you can already do that via a normal property
+  @property({ observer: TestElement.prototype.onBazChanged })
+  baz: string = 'test';
+
+  private onBazChanged(newValue: string, oldValue: string) {
+  }
+
   // @query replaces the property with a getter that querySelectors() in
   // the shadow root. Use this for type-safe access to internal nodes.
   @query('h1')

diff --git a/src/decorators.ts b/src/decorators.ts
@@ -42,6 +42,7 @@ export interface PropertyOptions {
   notify?: boolean;
   reflectToAttribute?: boolean;
   readOnly?: boolean;
+  observer?: string|((val: any, old: any) => void);
 }
 
 /**